Reservoir timescales for anthropogenic CO2 in the atmosphere

Non-steady state timescales are complicated and their application to specific geophysical systems requires a common theoretical foundation. We first extend reservoir theory by quantifying the difference between turnover time and transit time (or residence time) for time-dependent systems under any mixing conditions. We explicitly demonstrate the errors which result from assuming these timescales are equal, which is only true at steady state. We also derive a new response function which allows the calculation of age distributions and timescales for well-mixed reservoirs away from steady state, and differentiate between timescales based on gross and net fluxes. These theoretical results are particularly important to tracer-calibrated "box models" currently used to study the carbon cycle, which usually approximate reservoirs as well-mixed. We then apply the results to the important case of anthropogenic CO2 in the atmosphere, since timescales describing its behavior are commonly used but ambiguously defined. All relevant timescales, including lifetime, transit time, and adjustment time, are precisely defined and calculated from data and models. Apparent discrepancies between the current, empirically determined turnover time of 30-60 years and longer model-derived estimates of expected lifetime and adjustment time are explained within this theoretical framework. We also discuss the results in light of policy issues related to global warming, in particular since any comparisons of the "lifetimes" of different greenhouse gases (CO2, CH4, N2O, CFC's etc.) must use a consistent definition to be meaningful.     

Distribution of moderately volatile trace elements in fine-grained chondrule rims in the unequilibrated CO3 chondrite, ALH A77307

The concentrations of Ni, Cu, Zn, Ga, Ge, and Se in five, fine-grained chondrule rims in the highly unequilibrated CO3 chondrite ALH A77307 (3.0) have been determined for the first time by synchrotron X-ray fluorescence (SXRF) microprobe at Brookhaven National Laboratory. These elements are especially useful for tracing the role of condensation and evaporation processes which occurred at moderate temperatures in the solar nebula. Understanding the distribution of moderately volatile elements between matrix and chondrules is extremely important for evaluating the different models for the volatile depletions in chondritic meteorites. The data show that the trace element chemistry of rims on different chondrules is remarkably similar, consistent with data obtained for the major and minor elements by electron microprobe. These results support the idea that rims are not genetically related to individual chondrules, but all sampled the same reservoir of homogeneously mixed dust. Of the trace elements analyzed, Zn and Ga show depletions relative to CI chondrite values, but in comparison with bulk CO chondrites all the elements are enriched by approximately 1.5 to 3.5 x CO. The abundance patterns for moderately volatile elements in ALH A77307 chondrule rims closely mimic those observed in the bulk chondrite, indicating that matrix is the major reservoir for these elements. The close matching of the patterns for the volatile depleted bulk chondrite and enriched matrix is especially striking for Na, which is anomalously depleted in ALH A77307 in comparison with average CO chondrite abundances. The depletion in Na is probably attributable to the effects of leaching in Antarctica. With the exception of Na, the volatile elements show a relatively smooth decrease in abundance as a function of condensation temperature, indicating that their behavior is largely controlled by their volatility.     

我国第一个24位数字化无线遥测地震台网──广州台网通过验收

由广东省人民政府、珠江三角洲地区各市政府和国家地震局共同投资兴建的广州数字化遥测地震台网（以下简称广州台网），1985年开始筹建，1989年开始设备引进，经过安装调试、信道改造、系统完善和试验运行等多个环节，作了大量技术工作，现已完成了全部建设过程，达到了组织验收要求。1996年12月17～20日，由国家地震局和广东省人民政府联合组成的以陈运泰院士为组长的验收组对广州台网进行了测试和验收。验收组听取和审阅了广州台网技术人员作的技术、考核运行和工作报告，以及测试组作的测试报告，实地检查了台网技术系统的运行情况并进行…     

三水发生M_L3.7和4.2级地震

1997年9月23日11时20分，广东省三水市南边镇（北纬23．2°，东经113°），发生ML3，7级地震，9月26日13时27分，再发生ML4．2级（北纬23．3°，东经113°）地震一次。这是建国以来珠三角地区发生的最大一次地震。今年投入正式观测的广州遥测地震台网在这两次地震速报中发挥了重要的作用。两次地震分别只用5分和9分钟就准确地测定了参数作出速报。我局同时将地震情况上报省政府和国家地震局，达到了国家地震局要求的大中城市附近发生强有感地震后匕分钟内作出速报的要求。这两次地震佛山市范围普遍有感，广州市区部分居民也有感，特别是9…     

广东省东部地区的S波速度结构

利用广东省数字遥测台网记录到的2000年11月16日发生在所罗门群岛的两次Ms7．7和Ms7．8地震及2000年11月18日新爱尔兰地区的Ms7．3地震面波波形数据，测定了在广东地区汕头和韶关之间路径上的相速度频散曲线并反演得到了对应的地壳横波速度结构。结果表明该地区的地壳厚度为30km，上地壳横波速度变化较大，中下地壳相对均匀，没有发现地壳内部的低速层。     

通用接口总线和地电自动测量系统(GP—IB和地电ATS)

微处理机(μp)和微型计算机(μc)近年来获得了迅猛发展,应用领域不断扩大.其中一个重要的领域是数字仪表。目前生产的数字仪表内部都装有一部或多部μp/μc.它们大有取代传统的模似仪表的趋势。数字仪表发展如此迅速的驱动力则是它的高精度,高速度,高稳定性,使用方便,应用广泛同时也因为各种各样的通用数字仪表可以很快的组成为实现各种不同目的,任务、要求的自动测试系统ATS(Automatic Test System).     

广东地区现代构造应力场的模拟计算

运用已知的断裂边界条件、区内震源机制解、小震应力降和环境应力场等资料作为基本数据,建立地质模型和计算模型,用有限元方法模拟计算了华南地区的现代地壳构造应力场.初步得到了本区的外力作用方式、断裂活动情况、应力集中状况、区应力场分布状况,为划分地震危险区段提供了依据.